1977). While the results of Gust’s study are restricted to the specific flexible 
chambers and conditions of his measurements, they show quite convincingly 
that it is possible to obtain a small scale turbulent spectrum in a chamber that 
is similar to that found in the surrounding coastal waters. Unfortunately, 
almost all of these turbulence measurements were made in a metabolic 
chamber used with benthic algae rather than in plankton studies, and no 
biological data were included. 
This paper reports the results of a number of turbulence experiments carried 
out at different times of the year using coupled benthic-pelagic microcosms 
designed as analoges of Narragansett Bay, R.I. While some of the data from 
experiments conducted during the spring have been reported previously (Perez 
et al 1977), we have now carried out identical studies during winter and 
summer months. In addition, we have explored in this paper a number of 
techniques for characterizing the turbulent mixing levels in the microcosms and 
compared them to the dissolution rate measurements used previously (Oviatt et 
al 1977, Perez et al 1977). Finally, we have attempted to carry out 
experiments to test our earlier conclusion that phytoplankton and zooplankton 
respond independently to different turbulence levels. The impression that the 
phytoplankton and zooplankton were not coupled in their response to 
turbulence was based on indirect evidence (Perez et al 1977) and we felt it 
desirable to test this conclusion directly by adjusting the levels of zooplankton 
in replicate tanks and observing whether concommitant but opposite changes 
would occur in the phytoplankton. 
METHODS 
The Microcosms 
The microcosms used in these experiments have been described in detail in 
earlier papers (Perez et al 1977; Oviatt et al 1977 and in press). Each 
microcosm consisted of a 166 liter plastic tank containing 150 1 of water (0.7 
m deep) collected by bucket from the lower West Passage of Narragansett Bay. 
This area of the bay shows a well mixed water column about 8 m deep with 
salinity between 28-3 l 0/ oo throughout the year. Characteristics of the bay have 
been described in some detail by Kremer and Nixon (1978). The microcosms 
were maintained in a running sea water bath in the laboratory near field 
temperatures and illuminated for the appropriate natural photoperiod by 
Westinghouse Cool White fluorescent lights. The response of the microcosms to 
light input is complex and the choice of a value for any particular experiment 
is difficult (Nixon et al, in press). The experiments described here were carried 
out at 5-25 ly/day, values considerably below the average tight energy found in 
the water column of the bay. 
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